public class ParamTest {
    public static void main(String[] args) {
        // 测试1. 方法不能修改数值参数
        System.out.println("Testing tripleValue:");
        double percent = 10;
        System.out.println("Before: percent=" + percent);
        tripleValue(percent);
        System.out.println("After: percent=" + percent);

        // 测试2. 方法可以修改对象参数
        System.out.println("\nTesting tripleSalary:");
        var harry = new Employee("Harry", 50000);
        System.out.println("Before: salary=" + harry.getSalary());
        tripleSalary(harry);
        System.out.println("After: salary=" + harry.getSalary());

        // 测试3. 方法不能附加新对象到对象参数
        System.out.println("\nTesting swap:");
        var a = new Employee("Alice", 50000);
        var b = new Employee("Bob", 50000);
        System.out.println("Before: a=" + a.getName());
        System.out.println("Before: b=" + b.getName());
        swap(a, b);
        System.out.println("After: a=" + a.getName());
        System.out.println("After: b=" + b.getName());
    }

    public static void tripleValue(double x) {
        x = 3.0 * x;
        System.out.println("End of method: x is " + x);
    }

    public static void tripleSalary(Employee x) {
        x.raiseSalary(200);
        System.out.println("End of method: salary is " + x.getSalary());
    }

    public static void swap(Employee x, Employee y) {
        Employee temp = x;
        x = y;
        y = temp;
        System.out.println("End of method: x is " + x.getName());
        System.out.println("End of method: y is " + y.getName());
    }
}

class Employee {
    private String name;
    private double salary;

    public Employee(String n, double s) {
        name = n;
        salary = s;
    }

    public String getName() {
        return name;
    }

    public double getSalary() {
        return salary;
    }

    public void raiseSalary(double byPercent) {
        double raise = salary * byPercent / 100;
        salary += raise;
    }
}
